Heretofore, a photosensitive ceramic composition has been proposed as a photosensitive ceramic composition for use in a laminated ceramic capacitor, for example, which contains
(a) ceramic powder (e.g., alumina, titanate, zirconate, stannate, BaTiO3, CaTiO3, SrTiO3, PbTiO3, CaZrO3, BaZrO3, CaSnO3, BaSnO3, and Al2O3),
(b) an inorganic binding aid (having a glass transition temperature of 550 to 825° C., particularly preferably 575 to 750° C.),
(c) a polymer (e.g., alkyl acrylate, alkyl methacrylate, ethylene unsaturated carboxylic acid, an amine or silane-containing compound),
(d) a photopolymerization initiator,
(e) a photocurable monomer, and
(f) an organic medium (Patent Document 1).
The use of the photosensitive ceramic composition of Patent Document 1 allows fine processing by photolithography and formation of a film of a dense pattern.
However, an insulating layer having a high dielectric constant can be formed when BaTiO3 or the like is used as ceramic powder in a dielectric material in the case of the photosensitive ceramic composition disclosed in Patent Document 1. Also, temperature characteristics of dielectric constant are not disclosed. Thus, under the actual circumstances, the photosensitive ceramic composition disclosed in Patent Document 1 cannot be sufficiently used in an application requiring that the temperature characteristics of dielectric constant are favorable.
A porcelain dielectric material for temperature compensation has been proposed as a porcelain dielectric material for temperature compensation considering temperature characteristics of dielectric constant, which contains
(a) a composition containing 2.5 to 17.5 mol % of BaO, 50.0 to 75.0 mol % of TiO2, and 15.0 to 47.5 mol % of Nd2O3 (excluding 10.0 to 12.5 mol % of BaO, 50.0 to 55.0 mol % of TiO2, 12.5 to 15.0 mol % of BaO, 50.0 to 57.5 mol % of TiO2, 15.0 to 17.5 mol % of BaO, 50.0 to 60.0 mol % of TiO2], and (b) 7.4 to 20.0% of Bi2O3 (Patent Document 2).
When the porcelain dielectric material for temperature compensation is used, a sintered compact having favorable temperature characteristics of dielectric constant can be obtained. However, the porcelain dielectric material for temperature compensation is not a photosensitive material. Therefore, there arises a problem in that it is hard to perform fine processing, which can be performed by photolithography of a photosensitive paste. Moreover, there also arises a problem in that since a glass ingredient is not present and the sintering temperature is as high as 1000° C. or more (1270 to 1400° C.), the equipment and energy costs in a burning process are high.
[Patent Document 1] Japanese Patent No. 1660875 (Japanese Examined Patent Application Publication No. 3-23514)
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 49-120200